Large Ionic Currents Leave the Primitive Streak of the 7.5-Day Mouse Embryo

1989 ◽  
Vol 176 (2S) ◽  
pp. 110-117 ◽  
Author(s):  
GLEN K. WINKEL ◽  
RICHARD NUCCITELLI
Keyword(s):  
Mouse Embryo ◽  
Ionic Currents ◽  
Primitive Streak

scholarly journals Spatiotemporal sequence of mesoderm and endoderm lineage segregation during mouse gastrulation

2020 ◽  
Author(s):  
Simone Probst ◽  
Sagar ◽  
Jelena Tosic ◽  
Carsten Schwan ◽  
Dominic Grün ◽  
...  
Keyword(s):  
Mouse Embryo ◽  
Primitive Streak ◽  
Cell Types ◽  
Complete Separation ◽  
Embryonic Cell ◽  
Spatiotemporal Pattern ◽  
Cell Lineages ◽  
Dependent Cell ◽  
Summary Statement ◽  
Germ Layer Formation

AbstractAnterior mesoderm (AM) and definitive endoderm (DE) progenitors represent the earliest embryonic cell types that are specified during germ layer formation at the primitive streak (PS) of the mouse embryo. Genetic experiments indicate that both lineages segregate from Eomes expressing progenitors in response to different NODAL signaling levels. However, the precise spatiotemporal pattern of the emergence of these cell types and molecular details of lineage segregation remain unexplored. We combined genetic fate labeling and imaging approaches with scRNA-seq to follow the transcriptional identities and define lineage trajectories of Eomes dependent cell types. All cells moving through the PS during the first day of gastrulation express Eomes. AM and DE specification occurs before cells leave the PS from discrete progenitor populations that are generated in distinct spatiotemporal patterns. Importantly, we don’t find evidence for the existence of progenitors that co-express markers of both cell lineages suggesting an immediate and complete separation of AM and DE lineages.Summary statementCells lineages are specified in the mouse embryo already within the primitive streak where Mesp1+ mesoderm and Foxa2+ endoderm are generated in a spatial and temporal sequence from unbiased progenitors.

Embryonic axis orientation in the mouse and its correlation with blastocyst relationships to the uterus

Development ◽  
1985 ◽  
Vol 89 (1) ◽  
pp. 15-35
Author(s):  
L. J. Smith
Keyword(s):  
Mouse Embryo ◽  
Three Dimensional ◽  
Primitive Streak ◽  
Positional Information ◽  
Uterine Horn ◽  
The Other ◽  
Dimensional System ◽  
Fate Map ◽  
Axis Orientation ◽  
Three Dimensional System

Each of the three primary axes of the primitive streak (6¾ days p.c.) to C-shaped (9½ days) stage mouse embryo has a specific relationship to the uterine horn axes. By a retrograde analysis of younger sectioned embryos it has been possible to construct an axis fate map for the implanting 4¼-day blastocyst and to show how its implantation in one or the other of two specific orientations to the ends and walls of the horn leads to these embryo-horn relationships. The implanting blastocyst axis fate map can be related to an axis fate map of the attached blastocyst (Smith, 1980) since these too are in one or the other of two orientations to the ends and walls of the horn. It is suggested that the asymmetries of the attached and implanting blastocysts that allowed the distinctive attachment and implantation orientations to be recognized, are the initial expressions of a three-dimensional system of positional information that is present in the attached blastocyst.

scholarly journals ?-catenin signaling marks the prospective site of primitive streak formation in the mouse embryo

2004 ◽  
Vol 231 (2) ◽  
pp. 416-424 ◽  
Author(s):  
Othman A. Mohamed ◽  
Hugh J. Clarke ◽  
Daniel Dufort
Keyword(s):  
Mouse Embryo ◽  
Primitive Streak

Misexpression of Cwnt8C in the mouse induces an ectopic embryonic axis and causes a truncation of the anterior neuroectoderm

Development ◽  
1997 ◽  
Vol 124 (15) ◽  
pp. 2997-3005 ◽  
Author(s):  
H. Popperl ◽  
C. Schmidt ◽  
V. Wilson ◽  
C.R. Hume ◽  
J. Dodd ◽  
...  
Keyword(s):  
Mouse Embryo ◽  
Primitive Streak ◽  
Primitive Endoderm ◽  
Morphological Examination ◽  
Expression Domain ◽  
Anterior Aspect ◽  
Beta Actin ◽  
Early Expression ◽  
Actin Promoter ◽  
Transgenic Embryos

Transgenic embryos expressing Cwnt8C under the control of the human beta-actin promoter exhibit duplicated axes or a severely dorsalised phenotype. Although the transgene was introduced into fertilised eggs all duplications occurred within a single amnion and, therefore, arose from the production of more than one primitive streak at the time of gastrulation. Morphological examination and the expression of diagnostic markers in transgenic embryos suggested that ectopic Cwnt8C expression produced only incomplete axis duplication: axes were always fused anteriorly, there was a reduction in tissue rostral to the anterior limit of the notochord, and no duplicated expression domain of the forebrain marker Hesx1 was observed. Anterior truncations were evident in dorsalised transgenic embryos containing a single axis. These results are discussed in the light of the effects of ectopic Xwnt8 in Xenopus embryos, where its early expression leads to complete axis duplication but expression after the mid-blastula transition causes anterior truncation. It is proposed that while ectopic Cwnt8C in the mouse embryo can duplicate the primitive streak and node this only produces incomplete axis duplication because specification of the anterior aspect of the axis, as opposed to maintenance of anterior character, is established by interaction with anterior primitive endoderm rather than primitive streak derivatives.

HNF3beta and Lim1 interact in the visceral endoderm to regulate primitive streak formation and anterior-posterior polarity in the mouse embryo

Development ◽  
1999 ◽  
Vol 126 (20) ◽  
pp. 4499-4511 ◽  
Author(s):  
A. Perea-Gomez ◽  
W. Shawlot ◽  
H. Sasaki ◽  
R.R. Behringer ◽  
S. Ang
Keyword(s):  
Mouse Embryo ◽  
Primitive Streak ◽  
Axis Formation ◽  
Visceral Endoderm ◽  
Primary Defect ◽  
Homozygous Mutant ◽  
Early Mouse ◽  
Mesoderm Patterning ◽  
Anterior Posterior ◽  
Anterior Visceral Endoderm

Recent embryological and genetic experiments have suggested that the anterior visceral endoderm and the anterior primitive streak of the early mouse gastrula function as head- and trunk-organising centers, respectively. Here, we report that HNF3beta and Lim1 are coexpressed in both organising centers suggesting synergistic roles of these genes in regulating organiser functions and hence axis development in the mouse embryo. To investigate this possibility, we generated compound HNF3beta and Lim1 mutant embryos. An enlarged primitive streak and a lack of axis formation were observed in HNF3beta (−)(/)(−);Lim1(−)(/)(−), but not in single homozygous mutant embryos. Chimera experiments indicate that the primary defect in these double homozygous mutants is due to loss of activity of HNF3beta and Lim1 in the visceral endoderm. Altogether, these data provide evidence that these genes function synergistically to regulate organiser activity of the anterior visceral endoderm. Moreover, HNF3beta (−)(/)(−);Lim1(−)(/)(−) mutant embryos also exhibit defects in mesoderm patterning that are likely due to lack of specification of anterior primitive streak cells.

scholarly journals Control of early anterior-posterior patterning in the mouse embryo by TGF-β signalling

2003 ◽  
Vol 358 (1436) ◽  
pp. 1351-1358 ◽  
Author(s):  
Elizabeth J. Robertson ◽  
Dominic P. Norris ◽  
Jane Brennan ◽  
Elizabeth K. Bikoff
Keyword(s):  
Mouse Embryo ◽  
Transforming Growth Factor ◽  
Organizer Region ◽  
Primitive Streak ◽  
Transforming Growth Factor Β ◽  
Axis Formation ◽  
Posterior Side ◽  
Molecular Pattern ◽  
Discrete Population ◽  
Anterior Posterior

Prior to gastrulation the mouse embryo exists as a symmetrical cylinder consisting of three tissue layers. Positioning of the future anterior–posterior axis of the embryo occurs through coordinated cell movements that rotate a pre–existing proximal–distal (P–D) axis. Overt axis formation becomes evident when a discrete population of proximal epiblast cells become induced to form mesoderm, initiating primitive streak formation and marking the posterior side of the embryo. Over the next 12–24 h the primitive streak gradually elongates along the posterior side of the epiblast to reach the distal tip. The most anterior streak cells comprise the ‘organizer’ region and include the precursors of the so–called ‘axial mesendoderm’, namely the anterior definitive endoderm and prechordal plate mesoderm, as well as those cells that give rise to the morphologically patent node. Signalling pathways controlled by the transforming growth factor–β ligand nodal are involved in orchestrating the process of axis formation. Embryos lacking nodal activity arrest development before gastrulation, reflecting an essential role for nodal in establishing P–D polarity by generating and maintaining the molecular pattern within the epiblast, extraembryonic ectoderm and the visceral endoderm. Using a genetic strategy to manipulate temporal and spatial domains of nodal expression reveals that the nodal pathway is also instrumental in controlling both the morphogenetic movements required for orientation of the final axis and for specification of the axial mesendoderm progenitors.

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